Re: Gary et al- ferrite question-FARMERIK

Russ Edmunds

The screw terminals are configured for an external longwire antenna, and they probably wouldn't work as well with a loop. If you're thinking about substituting a larger external loopstick in place of the existing internal one, that might work, although you may also encounter overloading because the circuitry may not be able to handle the increased signal.

Russ Edmunds
15 mi NW Phila
Grid FN20id

AM: Modified Sony ICF2010's (2) barefoot w/whip
FM: Yamaha T-80 & T-85, each w/ Conrad RDS Decoder;
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On Wed, Feb 4, 2015 at 3:43 PM, farmerik@... [ultralightdx] <ultralightdx@...> wrote:

I know Gary is an expert on adding larger ferrite antennas outside the cases of ULR's, so I thought I'd ask about improving Hi-Fi AM tuners the same way. One of my sets has leads from the ferrite loop stick long enough to mount it on top of the case instead of mostly inside the back of a metal case where it must be shielded. Then the loop stick could be rotated to pick up in different directions.  There are only two wires/one winding on the loop stick which is tuned by a section of the variable tuning cap and connects to the RF amp tube. There are also screw connections for an external AM antenna and ground. The external antenna screw has a fixed cap on either side of where the tuned loop stick circuit connects between the tube and antenna screw. I REALLY do not understand radio theory. So my questions are would a short winding on the loop stick likely be a better way to connect an external antenna and prevent it from picking up other signals or noise?

Also, how could I shield the loop stick very well so only the external antenna feeds in signals?

 My guess is steel/iron would interact with the magnetic field, not just shield the coil. I am thinking something like an IF shield can, but it may be a loaf baking pan I can set over the ferrite antenna and connect with a ground wire to the chassis. I have no fabrication skills, it has to be very simple.


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